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Avalanche Forecast

Dec 5th, 2023–Dec 6th, 2023
Alpine
4: High
The avalanche danger rating in the alpine will be high
Treeline
4: High
The avalanche danger rating at treeline will be high
Below Treeline
3: Considerable
The avalanche danger rating below treeline will be considerable
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
1: Low
The avalanche danger rating below treeline will be low

Regions: Bonnington, Crawford, Grohman, Kokanee, Kootenay Boundary, Kootenay Pass, Norns, Retallack, Rossland, Valhalla, Whatshan, Ymir.

Travel in avalanche terrain is not recommended during this warm and intense storm. A natural avalanche cycle may be ongoing.

Confidence

High

Avalanche Summary

Explosives triggered large wet loose avalanches on Tuesday. We expect that a natural avalanche cycle occurred on the buried weak layer of surface hoar described in the Snowpack Summary but we will have to wait for clearing skies for further observations. Continuing stormy conditions may continue this natural cycle wherever the weak layer remains intact.

Snowpack Summary

Stormy conditions continue with a high freezing level. Rain has soaked most of the snowpack to the mountain tops, which will switch to snow as the freezing level drops. This is loading between 10 to 30 cm of snow that overlies a touchy weak layer of feathery surface hoar. The intense storm is likely triggering many avalanches on this layer and perhaps squashing the layer elsewhere, but it may still linger in specific locations.

The remainder of the snowpack is generally weak and faceted, with a hard melt-freeze crust found near the base of the snowpack.

Snowpack depths are generally between 50 and 80 cm at treeline, which quickly tapers as you lower with elevation.

Weather Summary

Tuesday Night

Cloudy with 15 to 30 mm of rain or heavy snow near the mountain tops. Southwest alpine wind 20 to 40 km/h. Treeline temperature 1 °C. Freezing level 2300 m.

Wednesday

Cloudy with 15 to 30 cm of heavy snow or rain below the snow-rain line. Southwest alpine wind 20 to 30 km/h. Treeline temperature 0 °C. Freezing level 1900 m.

Thursday

Mostly cloudy with 5 to 15 cm of early-morning snow. West alpine wind 10 km/h. Treeline temperature -5 °C.

Friday

Mostly cloudy with 2 to 5 cm of snow. West alpine wind 10 to 20 km/h. Treeline temperature -7 °C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Avoid avalanche terrain during periods of heavy rain.
  • Be aware of the potential for larger than expected storm slabs due to the presence of buried surface hoar.
  • If triggered loose wet avalanches may step down to deeper layers resulting in larger avalanches.
  • Early season avalanches at any elevation have the potential to be particularly dangerous due to obstacles that are exposed or just below the surface.

Avalanche Problems

Storm Slabs

Rain and heavy snow are rapidly loading a buried weak layer. Storm slab avalanches may release naturally. The most problematic terrain features will be wherever the snow surface is relatively smooth and uniform.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely - Very Likely

Expected Size: 1 - 2

Loose Wet

Loose wet avalanches are likely wherever you find a saturated snowpack.

Aspects: All aspects.

Elevations: Treeline, Below Treeline.

Likelihood: Very Likely

Expected Size: 1 - 1.5